Stratosphere‐troposphere exchange: A review, and what we have learned from STACCATO

This paper provides a review of stratosphere‐troposphere exchange (STE), with a focus on processes in the extratropics. It also addresses the relevance of STE for tropospheric chemistry, particularly its influence on the oxidative capacity of the troposphere. After summarizing the current state of knowledge, the objectives of the project Influence of Stratosphere‐Troposphere Exchange in a Changing Climate on Atmospheric Transport and Oxidation Capacity (STACCATO), recently funded by the European Union, are outlined. Several papers in this Journal of Geophysical Research – Atmospheres special section present the results of this project, of which this paper gives an overview. STACCATO developed a new concept of…